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genirq: Get rid of unnecessary irqaction field in task_struct 

When a new thread handler is created, an irqaction is passed to it as
data. Not only that irqaction is stored in task_struct by the handler
for later use, but also a structure associated with the kernel thread
keeps this value as long as the thread exists.

This fix kicks irqaction out off task_struct. Yes, I introduce new bit
field. But it allows not only to eliminate the duplicate, but also
shortens size of task_struct.

Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Link: http://lkml.kernel.org/r/20120309135925.GB2114@dhcp-26-207.brq.redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Alexander Gordeev 2012-03-09 14:59:26 +01:00 committed by Thomas Gleixner
parent 540b60e24f
commit 4bcdf1d0b6
2 changed files with 16 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
include/linux/sched.h
View File

@ -1319,6 +1319,11 @@ struct task_struct {
unsigned sched_reset_on_fork:1; unsigned sched_reset_on_fork:1;
unsigned sched_contributes_to_load:1; unsigned sched_contributes_to_load:1;
#ifdef CONFIG_GENERIC_HARDIRQS
/* IRQ handler threads */
unsigned irq_thread:1;
#endif
pid_t pid; pid_t pid;
pid_t tgid; pid_t tgid;
@ -1427,11 +1432,6 @@ struct task_struct {
* mempolicy */ * mempolicy */
spinlock_t alloc_lock; spinlock_t alloc_lock;
#ifdef CONFIG_GENERIC_HARDIRQS
/* IRQ handler threads */
struct irqaction *irqaction;
#endif
/* Protection of the PI data structures: */ /* Protection of the PI data structures: */
raw_spinlock_t pi_lock; raw_spinlock_t pi_lock;

19
kernel/irq/manage.c
View File

@ -780,7 +780,7 @@ static int irq_thread(void *data)
handler_fn = irq_thread_fn; handler_fn = irq_thread_fn;
sched_setscheduler(current, SCHED_FIFO, &param); sched_setscheduler(current, SCHED_FIFO, &param);
current->irqaction = action; current->irq_thread = 1;
while (!irq_wait_for_interrupt(action)) { while (!irq_wait_for_interrupt(action)) {
@ -818,10 +818,10 @@ static int irq_thread(void *data)
irq_finalize_oneshot(desc, action, true); irq_finalize_oneshot(desc, action, true);
/* /*
* Clear irqaction. Otherwise exit_irq_thread() would make * Clear irq_thread. Otherwise exit_irq_thread() would make
* fuzz about an active irq thread going into nirvana. * fuzz about an active irq thread going into nirvana.
*/ */
current->irqaction = NULL; current->irq_thread = 0;
return 0; return 0;
} }
@ -832,27 +832,30 @@ void exit_irq_thread(void)
{ {
struct task_struct *tsk = current; struct task_struct *tsk = current;
struct irq_desc *desc; struct irq_desc *desc;
struct irqaction *action;
if (!tsk->irqaction) if (!tsk->irq_thread)
return; return;
action = kthread_data(tsk);
printk(KERN_ERR printk(KERN_ERR
"exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n", "exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq); tsk->comm ? tsk->comm : "", tsk->pid, action->irq);
desc = irq_to_desc(tsk->irqaction->irq); desc = irq_to_desc(action->irq);
/* /*
* Prevent a stale desc->threads_oneshot. Must be called * Prevent a stale desc->threads_oneshot. Must be called
* before setting the IRQTF_DIED flag. * before setting the IRQTF_DIED flag.
*/ */
irq_finalize_oneshot(desc, tsk->irqaction, true); irq_finalize_oneshot(desc, action, true);
/* /*
* Set the THREAD DIED flag to prevent further wakeups of the * Set the THREAD DIED flag to prevent further wakeups of the
* soon to be gone threaded handler. * soon to be gone threaded handler.
*/ */
set_bit(IRQTF_DIED, &tsk->irqaction->flags); set_bit(IRQTF_DIED, &action->flags);
} }
static void irq_setup_forced_threading(struct irqaction *new) static void irq_setup_forced_threading(struct irqaction *new)